Studies on the synthesis of the toxins, pardaxin, δ-toxin and their analogues by solid-phase methods

Abstract

Studies in our laboratory have been directed towards understanding the mechanism of action of two hydrophobic toxins, pardaxin comprising 33 residues and δ-toxin comprising 26 residues. Since isolation of these peptides in large amounts from natural sources is not convenient, we have explored synthetic approaches to get these peptides as well as their analogs. We have used chemistry specific to fluorenylmethoxycarbonyl (Fmoc) andt-butyloxycarbonyl (Boc) amino acids. Synthesis specific for Fmoc amino acids was carried out manually as well as on a semi-automated continuous flow peptide synthesizer. Synthesis specific for Boc amino acids was carried out manually. The protocols used by us have yielded 15-33 residue peptides which are of high purity. Even in peptides where heterogeneity was present, pure peptide could be obtained in good yields using simple gradients in fast performance liquid chromatography. The synthesis of pardaxin, δ-toxin and several analogs should help in identifying the molecular determinants of biological activity.